It seems to have started with the 900. Despite is reputation for the 3 spool economics and benefits, the ME 3 elected to go with P&W GP 7000. The GP by all right should have been a second choice as it was an integration engine and at best it usually takes time to get it right.

The next one was more direct but obscured. The Trent 1000 failed to deliver its specifications (GE did as well though its a design choice that has that negative aspect to it (RR has the same issue on the RR 777 engines that is ensured not to manifest now by throttle thrust to clear out the ice if its built up)

What has emerged is that RR only a couple years in began to design a 75% new engine for the 787, to be called the 10. In the engine world, that is a vote of failure that its not worth trying to fix (they did use some of the elements form the 1000). So they gave up on the 1000 (which while supported will no longer be produced.

Then the blades corrosion issue began and they replaced the blades throughout the fleet.

That's been followed by IPC blade cracks and a number of emergency landings and diversions.

RR now says its a undetected harmonic in the flow patch.

As the Trent 7000 is a bleed air version of the Ten, those two are linked and the A330NEO has been delayed as there to have been problems and the 7000 was delayed. Despite virtually an all new engine with the latest tech inserts from the XWB, the fuel improvement was only 3% (and it had smoke issues in some thrust settings they had to get a waiver for, first I have heard of that occurring in a program_)

Any new engine should easily give you 5% improvement.

They are not sure now if those design elements from the 1000 are going to be an issue in the Ten and 7000. Keeping in mind this has developed over a pretty wide range of years now.

When RR got the current lot of A380 they promised big savings to Emirates (suddenly it was 5% better than the GP of which is was 2-3% behind.

While obscure, they had problems with it before it went on the first A380 and they now to have blade issues though those have not been stated as to what.

Emirates looks to be returning to the GP for their next group of A380s.

Some 40+ 787s have been grounded over the lack of engines. Norwegian is going to retrofit their 787-9s with Tens (leaving the 1000s for the -8 which probably allows a thrust reducing and better (easier on engine) less impact on fuel use)

3 Spool designs are more costly due to parts, the return has to be in better on wing performance (longevity) as well as fuel burn. GE and PW have surpassed that advantage with two spool. Cost to overhaul a 3 spool is more costly and you need to get a fuel burn and longevity return to overcome those added costs.

It seems the 3 spool is now a dead end as flows get more advanced either you can't model that well or its got limitations with older cooler engine ops.

Regardless RR is in a world of hurt and we don't know yet how the XWB is going to fare as the cracks vs the corrosion issue took something around 5 years to show up.

Rolls-Royce has developed a redesigned intermediate pressure compressor blade for its Trent 1000 engines, which addresses durability issues on Package C engines. Entry into service of the already certified new blade will take place on a phased basis as production ramps up.

"...On Thursday 17th Jan 2019, an All Nippon Airways Boeing 787-8 performing flight NH-985 from Tokyo Haneda to Osaka, landed on Itami's runway 32L, touched down, the crew deployed the thrust reversers when both engines (Trent 1000) rolled back and shut down. The aircraft rolled out without further incident, came to a stop about 2450 meters/8030 feet down the runway and was disabled. The aircraft was towed off the runway about 40 minutes after landing...."